Yes, I think what I did is the most I could do without Nintendo shutting down the project lol. As a "technical demo," I think it can still be protected as a non-profit artistic project... I think if I had done it in Godot 4, the project would have looked much better, since I could have used Vulkan or Direct3D, but back then I did it with Godot 3 which uses OpenGL, and OpenGL isn't exactly the best library for making 3D games, so optimization was a real challenge. Surprisingly, it uses raytracing, which is completely unnecessary, but I wanted to see how far I could push it: It doesn't have baked lighting, it's real-time lighting. I wanted to see how many enemies I could put on screen without frame drops, how many background elements I could add without performance tanking...
Obviously, the CRT effect helps a lot, since it lets me lower the game's resolution to give it that "retro" look, which is nice—I like it (I use it a lot)—but aside from personal taste, it was also an optimization technique. Because if I left the game in 16:9 and 1080p (or higher), not only would it have had frame drops on modest hardware, it wouldn't have looked as good without adding more decoration; it would have looked really empty.
In Godot 4, things change a lot; performance is much more stable with Vulkan or Direct3D. Even if I had added a lot more decoration and enemies, it would still run smoother.
But that's how it is—part of the magic isn't always adding more stuff, but making it look good with less. Still, it's necessary to do these kinds of experiments to learn the limits of the tools. 👍